Agree about national Pretenders. It's a pity that, say, Lawgiver for MA Mictlan is completely useless - it has recruitable Coatles which can do just antything he can. And he doesn't have a single special rule afair!
I like Divine Emperor for Pythium, though I didn't play this nation much lately. Void Lord for R'lyeh also. Master Lich is often both useful and thematic, and Ghost King can be thematic for most nations (though I would prefer the LA Arcoscephales to get their own special one - that of the "Great Conqueror" mentioned in their background)...